1. Field of the Invention
The present invention relates to a keyboard for a portable notebook computer capable of seeing keys even in low light conditions.
2. Description of the Related Art
As a notebook computer becomes thinner and lighter, consumers have found that such improvements make it easier to carry to a variety of different locations. Further, there has been a dramatic increase in battery capacity for portable notebooks, thereby allowing users to use a notebook computer for longer periods, often in a continuous format, of time. As a result, the use of a notebook computer in public, in transportation-based environments and outdoors has become more commonplace.
In general, when a keytop 92 of a key 90 on a keyboard of a notebook computer shown in FIG. 11 is pressed, a rubber member 96 is pushed downward with a pantograph 94. When a cup portion 98 of the rubber member 96 is thereby compressed, a protrusion 100 pushes a first contact 112a of an upper polyester film 104 downward, so that the first contact 112a comes in contact with a second contact 112b of a lower polyester film 106. When the two contacts 112a and 112b touch each other, electrical continuity between wirings on the films 104 and 106 is ensured (i.e., the path is conductive) and an electric signal is transmitted to a controller of the keyboard. From the transmitted electric signal, the controller judges which key 90 was pressed.
However, since it is hard for a user to visibly see the keys 90 in a dimly-lit environment, such as in an airplane, it is readily conceivable that a user is likely to make an incorrect key stroke often. As such, in order to overcome these errors, it would be useful to provide a lighting fixture to a keyboard so as to illuminate the keys 90.
For example, Japanese Unexamined Patent Publication No. (Patent Kokai No.) 11-232957 (1999) and 11-282606 (1999) disclose a key input device having a backlight for illuminating a keyboard. These input devices are for an electronic organizer and handy terminal, and comprise a backlight panel on a substrate or a sheet on which contacts and a circuit are formed. However, in the case of a keyboard of a notebook computer, projections 115 of a substrate 114, as in FIG. 11, would need to be inserted into holes bored through polyester films 104 and 106 and spacer 108 so as to keep a membrane 110 in a right position, as shown in FIG. 11. Unlike the aforementioned key input devices, holes cannot be bored into the backlight panel, so that the backlight panel cannot be placed on the membrane 110 to illuminate the keys 90.
As such, it would be desirable to provide a keyboard capable of enabling a user to better see keys in environments where there is typically an insufficient light source to allow normal viewing, such as in an airplance, for example.
Accordingly, an object of the present invention is to provide a keyboard capable of seeing keys even in environments where there is not sufficient light to see the keys, for example, in an airplane.
A keyboard, according to an aspect of the present invention comprises: a substrate; a membrane having contacts for each key formed on the substrate; an elastic member for each key formed over the contacts of the membrane; a keytop for each key formed over the elastic member; and light-emitting means for emitting light from the underside of the substrate to the keytops, wherein the substrate and the membrane are light transmissive at least at portions corresponding to the top surfaces of the keytops, and the keytops are light transmissive at portions corresponding to legends or non-legend areas of the top surfaces of the keytops.
In another aspect of the present invention, light emitted by the light-emitting means of the keyboard, formed under the substrate, passes through the substrate, membrane and elastic material to the keytops, to thereby provide for each keytop to appear lit.
Similarly, where a film-like circuit board having contacts for each key is used as a substrate for the membrane, light emitted by the light-emitting means formed under the substrate passes through the substrate, circuit board, elastic material, and keytops, such that each keytop appears to glow.
In another aspect of the present invention, the light-emitting means under the substrate can illuminate the keytops, thereby improving the likelihood of a user selecting the desired key such that the chance of an incorrect key stroke is reduced. In addition, the thermoelectric generating element is used as a power supply source for light source of the light-emitting means, so that battery duration is not reduced.